Provides an applet that demonstrates how the three angles of a triangle add to 180 degrees. Another applet at the bottom gives step-by-step instructions on how to do this activity with a piece of pap...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that show the relationship between the perimeter and area of a triangle.
It shows that a triangle with a constant perimeter does NOT have a constant...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that explain the area of a triangle. The applet shows a triangle that can be reshaped by dragging any vertex.
As it changes, the area is continuall...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that demonstrate the concept of congruent triangles.
Applets show that triangles are congruent if they are the same, rotated, or reflected.
In ea...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that shows how triangles that have
two angles and their included side the same must be congruent.
The applet shows two triangles, one of which can...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that shows how triangles that have
two sides and their included angle the same must be congruent.
The applet shows two triangles, one of which can...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that show how triangles that have
two angles and a non-included side the same must be congruent.
The applet shows two triangles, one of which can be...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that show how triangles that have all 3 sides the same length must be congruent.
The applet shows two triangles, one of which can be reshaped by dragg...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step animated instructions on how to
contruct 30-60-90 triangle with given base length
using only a compass and straightedge.
...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step instructions on how to find
a median of a triangle using only a compass and straightedge.
The method used involves bisecti...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step animated instructions on how to
construct a triangle given all three sides (SSS),
using only a compass and straightedge.
More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step animated instructions on how to
contruct a triangle given two angles and the included side length (ASA),
using only a compa...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step animated instructions on how to
contruct a triangle given two sides and the included angle (SAS),
using only a compass and ...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step instructions on how to find
the circumcircle of a triangle using only a compass and straightedge.
The method used involves...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step instructions on how to find
the centroid of a triangle using only a compass and straightedge.
The method used involves con...More: lessons, discussions, ratings, reviews,...

This sketch allows students to explore the Triangle Inequality Theorem, the sum of the lengths of 2 sides of a triangle are greater than the length of the 3rd side. By dragging vertices and looking a...More: lessons, discussions, ratings, reviews,...

This material is based upon work supported by the
National Science Foundation under Grant DUE-0226284.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s)
and do not necessarily reflect the views of the
National Science Foundation.